The cosmetic placing of color onto the nail of humans has loon been a desirable and part of the cosmetic world. The physical and chemical demands of color so applied are dramatic. Specifically, the following considerations need to be addressed (1) how to apply color in a film that is easy to applied in a process at ambient conditions; (2) how to obtain a cosmetically acceptable film, in terms of color clarity, and gloss; (3) how to maintain the film and the desirable properties that the consumer demands over a period of time that the film remains on the skin; (4) how to assure resistance to environmental insults the nails are subjected to during the lifetime of the polish; (5) and how to thoroughly remove the film efficiently and thoroughly when the consumer desires the removal, and finally how to do this in a cost effective way.
It must be clearly understood that the process of decorative application of color to the nails by a consumer is fundamentally different from painting a wall or other permanent film applications. Unlike the application of paint, nail colors need to be removable thoroughly and effectively at the whim of the consumer. The color is in many regards a fashion item and can change quite often in a short period of time.
This ability to be easily removed at any time, coupled with the need to be accomplished by the consumer in a home environment, places limitations upon the type of process that can be used, in terms of application technique (limited to brush application) at ambient conditions and using no special equipment.
In addition to need for facile application and removal as desired by the consumer, the films and the colors and other ingredients present in the film need to apply in a uniform film and remain functional and cosmetically acceptable on the nail in terms of scuffing, breaking when struck, pliable over the period of time during which they are on the nails. The film that forms in the above process must possess specific cosmetic benefits, including ability to disperse colors, be scuff resistant, resistant to cracking when struck, remain pliable and cosmetically appealing. One of the major properties the consumers finds appealing is gloss. Gloss in a film of this type is generally difficult to attain by adding ingredients. The inclusion of an aromatic components directly into the film. This is generally accomplished by adding into the reaction mixture, trimellitic anhydride. This aromatic anhydride alters the refractive index of the film providing gloss.
U.S. Pat. No. 4,301,046 issued in November 1981 to Mitchell Schlossman, a pioneer in the field, entitled Universal nail polish using polyester resin disclosed a nail polish is made from 92% to 96% ingredients including a film former, colorant, plasticizer and solvent; and 4% to 8% polyester resin made from 2,2,4-trimethyl-1,3-pentanediol, isophthalic acid-85, and trimellitic anhydride, having an acid value of 75-85 and a viscosity of 125-175 centipoise. In another example, the polyester is made from 50.932% 2,2,4 trimethyl-1,3-pentanediol, 27.579% isophthalic acid-85, 0.186% dibutyl tin oxide catalyst and 21.303 trimellitic anhydride, having an acid value of 80 and a viscosity of 150 centipoise.
The inclusion of silicone as a reactant in the polymer mixture results in many highly desirable attributes and makes a more cosmetically appealing film. Firstly, polymers containing silicone result in better more uniform films when applied to the nail. Not wanting to be bound by a single theory, this appears to be the result of a lowering of the surface tension of the film when applied. Secondly, polymers containing silicone are more flexible when applied to the nails, this makes them less likely to break upon a physical insult, and less likely to undergo a cut damage when sharp items are encountered by the film. Finally, polymers containing silicone are more easily removed with acetone, in part because they are easily wet out by the solvent in silicone is present, a result related to the low surface tension of silicone containing films, compared to non silicone containing films of comparable composition.